On the Existence of Water Turbulence Induced by Nonbreaking Surface Waves

2009 ◽  
Vol 39 (10) ◽  
pp. 2675-2679 ◽  
Author(s):  
Alexander V. Babanin ◽  
Brian K. Haus
Keyword(s):  
Energy Dissipation ◽  
Water Waves ◽  
Wave Breaking ◽  
Isotropic Turbulence ◽  
Wave Energy Dissipation ◽  
Numerical Studies ◽  
Direct Measurements ◽  
Image Velocimetry ◽  
Velocity Spectra ◽  
Wave Induced

Abstract This paper is dedicated to wave-induced turbulence unrelated to wave breaking. The existence of such turbulence has been foreshadowed in a number of experimental, theoretical, and numerical studies. The current study presents direct measurements of this turbulence. The laboratory experiment was conducted by means of particle image velocimetry, which allowed estimates of wavenumber velocity spectra beneath monochromatic nonbreaking unforced waves. Observed spectra intermittently exhibited the Kolmogorov interval associated with the presence of isotropic turbulence. The magnitudes of the energy dissipation rates due to this turbulence in the particular case of 1.5-Hz deep-water waves were quantified as a function of the surface wave amplitude. The presence of such turbulence, previously not accounted for, can affect the physics of the wave energy dissipation, the subsurface boundary layer, and the ocean mixing in a significant way.

Viscous flows in a muddy seabed induced by a solitary wave

2008 ◽  
Vol 598 ◽  
pp. 383-392 ◽  
Author(s):  
YONG SUNG PARK ◽  
PHILIP L.-F. LIU ◽  
STEPHEN J. CLARK
Keyword(s):  
Solitary Wave ◽  
Water Waves ◽  
Particle Image ◽  
Plug Flow ◽  
Viscous Flows ◽  
The Other ◽  
Viscous Layer ◽  
Shallow Water Waves ◽  
Image Velocimetry ◽  
Wave Induced

Liu & Chan (J. Fluid Mech. vol. 579, 2007, p. 467, hereinafter referred to as LC) derived analytical solutions for the interactions between shallow water waves and a viscous fluid seabed. In this paper we present a set of new experimental data on the solitary-wave-induced flows in a viscous muddy seabed so as to validate LC's theory and the approximations employed. In the experiments a clear silicone fluid was used as the viscous mud and particle image velocimetry was employed to measure the velocity field inside the viscous mud. The shear stress along the bottom of the mud bed and the displacement of the water--mud interface were also deduced from data. Experimental results showed excellent agreement with the theoretical solutions. Additional analyses were performed to show that the ratio of the muddy seabed thickness to the corresponding bottom boundary-layer thickness, $\dbar$, plays an important role in characterizing mud flow regimes. When $\dbar\,{\leq}\,1$, the vertical profile of the horizontal velocity in the mud bed can be parameterized as a parabola. On the other hand, when $\dbar\,{\gg}\,1$, the velocity profile appears as a plug flow above a thin viscous layer. When $ \dbar\,{\sim}\,O(1)$, the flow patterns are more complex than the other two regimes and flow reversal can occur inside the viscous mud bed.

scholarly journals Local Wave Energy Dissipation and Morphological Beach Characteristics along a Northernmost Segment of the Polish Coast

2018 ◽  
Vol 65 (2) ◽  
pp. 91-108
Author(s):  
Grzegorz Różyński
Keyword(s):  
Energy Dissipation ◽  
Wave Energy ◽  
Wave Breaking ◽  
Beach Profile ◽  
Sedimentary Characteristics ◽  
Wave Energy Dissipation ◽  
Equilibrium Beach Profile ◽  
Local Wave ◽  
Processing Techniques ◽  
Signal Processing Techniques

AbstractThis paper analyses cross-shore bathymetric profiles between Władysławowo (km 125 of the Polish coastal chainage) and Lake Sarbsko (km 174) done in 2005 and 2011. Spaced every 500 m, they cover beach topography from dune/cliff crests to a seabed depth of about 15 m. They were decomposed by signal processing techniques to extract the monotonic component of beach topography and to perform a straightforward assessment of wave energy dissipation rates. Three characteristic dissipation patterns were identified: one associated with large nearshore bars and 2–3 zones of wave breaking; a second, to which the equilibrium beach profile concept can be applied; and a third, characterized by mixed behaviour. An attempt was then made to interpret these types of wave energy dissipation in terms of local coastal morphological features and the underlying sedimentary characteristics.

scholarly journals Wave-Induced Accelerations of a Fish-Farm Elastic Floater: Experimental and Numerical Studies

2014 ◽  
Author(s):  
Peng Li ◽  
Odd M. Faltinsen ◽  
Marilena Greco
Keyword(s):  
Deep Water ◽  
Water Waves ◽  
Nonlinear Effects ◽  
Fish Farm ◽  
Frequency Domain Method ◽  
Frequency Dependency ◽  
Numerical Studies ◽  
Vertical Accelerations ◽  
Steep Waves ◽  
Wave Induced

Numerical simulations and experiments of an elastic circular collar of a floating fish farm are reported. The floater model without netting structure is moored with nearly horizontal moorings and tested in regular deep-water waves of different steepnesses and periods without current. Local overtopping of waves were observed in steep waves. The focus here is on the vertical accelerations along the floater in the different conditions. The experiments show that higher-order harmonics of the accelerations matter. A 3D weak-scatter model with partly nonlinear effects as well as a 3D linear frequency-domain method based on potential flow are used. From their comparison against the measurements, strong 3D and frequency dependency effects as well as flexible floater motions matter. The weak-scatter model can only partly explain the nonlinearities present in the measured accelerations.

scholarly journals WAVE ENERGY DISSIPATION IN ARBITRARILY SHAPED HARBOURS OF VARIABLE DEPTH

1986 ◽  
Vol 1 (20) ◽  
pp. 147 ◽  
Author(s):  
J.K. Kostense ◽  
K.L. Meijer ◽  
M.W. Dingemans ◽  
A.E. Mynett ◽  
P. Van den Bosch
Keyword(s):  
Water Waves ◽  
Arbitrary Shape ◽  
Element Model ◽  
Scale Model ◽  
Wave Excitation ◽  
Variable Depth ◽  
Wave Energy Dissipation ◽  
Long Wave ◽  
Wave Induced ◽  
Linear Water Waves

A finite element model for combined refraction-diffraction problems of linear water waves has been extended to include the effect of various dissipative mechanisms on wave excitation response in harbours of arbitrary shape and variable depth. Especially, the effects of bottom friction, partial absorption along the harbour, contours, and transmission through permeable breakwaters have been considered. Although, within the mild slope approximation, the model is valid for arbitrary wave lengths, in this paper its effectiveness for harbour design applications is demonstrated for long wave induced resonance phenomena. For this purpose a realistic harbour geometry has been selected. A hydraulic scale-model of this harbour enabled experimental verification of the computational results.

scholarly journals Wave-Induced Accelerations of a Fish-Farm Elastic Floater: Experimental and Numerical Studies

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Peng Li ◽  
Odd M. Faltinsen ◽  
Marilena Greco
Keyword(s):  
Water Waves ◽  
Three Dimensional ◽  
Nonlinear Effects ◽  
Fish Farm ◽  
Frequency Domain Method ◽  
Frequency Dependency ◽  
Numerical Studies ◽  
Vertical Accelerations ◽  
Steep Waves ◽  
Wave Induced

Numerical simulations and experiments of an elastic circular collar of a floating fish farm are reported. The floater model without netting structure is moored with nearly horizontal moorings and tested in regular deep-water waves of different steepnesses and periods without current. Local overtopping of waves was observed in steep waves. The focus here is on the vertical accelerations along the floater in the different conditions. The experiments show that higher-order harmonics of the accelerations matter. A three-dimensional (3D) weak-scatter model with partly nonlinear effects as well as a 3D linear frequency-domain method based on potential flow are used. From their comparison against the measurements, strong 3D and frequency dependency effects as well as flexible floater motions matter. The weak-scatter model can only partly explain the nonlinearities present in the measured accelerations.

scholarly journals Estimation of Kinetic Energy Dissipation from Breaking Waves in the Wave Crest Region

2017 ◽  
Vol 47 (5) ◽  
pp. 1145-1150 ◽  
Author(s):  
J. H. Lee ◽  
J. P. Monty ◽  
J. Elsnab ◽  
A. Toffoli ◽  
A. V. Babanin ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Isotropic Turbulence ◽  
Breaking Waves ◽  
Wave Crest ◽  
Shear Stresses ◽  
Surface Shear ◽  
Phase Dependence ◽  
Dissipation Rates ◽  
Velocity Spectra

AbstractWave-induced turbulence due to breaking in the absence of surface shear stresses is investigated experimentally. A high-fidelity particle image velocimetry (PIV) technique is used to measure the turbulence near the water surface, inside the wave crests. The spatial velocity vector fields of the breaking waves acquired from PIV provide accurate vertical velocity profiles near the air–water interface, as well as wavenumber velocity spectra beneath the breaking waves at different depths. These velocity spectra exhibit a Kolmogorov interval at high wavenumbers, indicating the presence of isotropic turbulence and permitting an estimation of energy dissipation rates. The depth dependence of dissipation rates of the breaking waves generated in the laboratory shows a scaling similar to that found in wind-forced breaking waves in the field. A phase dependence in the dissipation rates of turbulence kinetic energy is also observed, which should be considered to improve the accuracy of the estimated and modeled wave energy dissipation.

scholarly journals Correlation between Buoyancy Flux, Dissipation and Potential Vorticity in Rotating Stratified Turbulence

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 157
Author(s):  
Duane Rosenberg ◽  
Annick Pouquet ◽  
Raffaele Marino
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Potential Vorticity ◽  
Isotropic Turbulence ◽  
Joint Probability ◽  
Buoyancy Flux ◽  
Turbulent Regime ◽  
Stratified Turbulence ◽  
Low Dissipation ◽  
Linear And Nonlinear

We study in this paper the correlation between the buoyancy flux, the efficiency of energy dissipation and the linear and nonlinear components of potential vorticity, PV, a point-wise invariant of the Boussinesq equations, contrasting the three identified regimes of rotating stratified turbulence, namely wave-dominated, wave–eddy interactions and eddy-dominated. After recalling some of the main novel features of these flows compared to homogeneous isotropic turbulence, we specifically analyze three direct numerical simulations in the absence of forcing and performed on grids of 10243 points, one in each of these physical regimes. We focus in particular on the link between the point-wise buoyancy flux and the amount of kinetic energy dissipation and of linear and nonlinear PV. For flows dominated by waves, we find that the highest joint probability is for minimal kinetic energy dissipation (compared to the buoyancy flux), low dissipation efficiency and low nonlinear PV, whereas for flows dominated by nonlinear eddies, the highest correlation between dissipation and buoyancy flux occurs for weak flux and high localized nonlinear PV. We also show that the nonlinear potential vorticity is strongly correlated with high dissipation efficiency in the turbulent regime, corresponding to intermittent events, as observed in the atmosphere and oceans.

Resonant reflection of surface water waves by periodic sandbars

1985 ◽  
Vol 152 ◽  
pp. 315-335 ◽  
Author(s):  
Chiang C. Mei
Keyword(s):  
Water Waves ◽  
Resonance Condition ◽  
Nonlinear Effects ◽  
Sea Bottom ◽  
Strong Reflection ◽  
Weak Reflection ◽  
Surface Water Waves ◽  
Wave Induced ◽  
Incident Waves ◽  
Resonant Reflection

One of the possible mechanisms of forming offshore sandbars parallel to a coast is the wave-induced mass transport in the boundary layer near the sea bottom. For this mechanism to be effective, sufficient reflection must be present so that the waves are partially standing. The main part of this paper is to explain a theory that strong reflection can be induced by the sandbars themselves, once the so-called Bragg resonance condition is met. For constant mean depth and simple harmonic waves this resonance has been studied by Davies (1982), whose theory, is however, limited to weak reflection and fails at resonance. Comparison of the strong reflection theory with Heathershaw's (1982) experiments is made. Furthermore, if the incident waves are slightly detuned or slowly modulated in time, the scattering process is found to depend critically on whether the modulational frequency lies above or below a threshold frequency. The effects of mean beach slope are also studied. In addition, it is found for periodically modulated wave groups that nonlinear effects can radiate long waves over the bars far beyond the reach of the short waves themselves. Finally it is argued that the breakpoint bar of ordinary size formed by plunging breakers can provide enough reflection to initiate the first few bars, thereby setting the stage for resonant reflection for more bars.

Sign in / Sign up

Export Citation Format

Share Document